Manufacture of indoxyl, its homologues and their derivatives.



UNITED s 'rAtrEs PATENT curios.

EMMANUEL ANDRE BOURCART, F PARIS, FRANCE, ASSIGNOR, BY MESNE ASSIGN- MENTS, Tl.) COMPAGNIE NATIONALE DE MATIEEES COLORANTES ET DE PRODUITS GI-IIMIQUES, OF PARIS, FRANCE, A CORPORATION OF FRANCE.

MANUFACTURE OF INDOXYL, ITS

ification of Letters Patent.

HOMOLOGU'ES AND THEIR DERIVATIVES.

Patented Feb. ii, isle.

No Drawing. Application filed August 1. 1916. Serial No. 112.589. Renewed October 10. 1918. Serial 0.257.668.

l c To all whom it may concern;

Be it known that I, EMMANUEL Anmni Bouncers, of 2 Rue Blanche, Paris, France, chemist, have invented new and useful Improvements in the Manufacture of Ind oxyl,

its Homologues and Their Derivatives, which improvements are fullysct forth in the following specification.

The manufacture of synthetic indigo by the fusion of phenyl glyciu with caustic potash as proposed by Heumann has not proved commercially practicable because the maximum yield obtained is 10% of the weight of the glycin.

the hydrids, nitrids, alkali alcoholates, allialine earths, their oxide and carbid of calcium at temperatures ranging between 190 and 280 centrigrade has increased the yield so that some of the processes have been worked commercially.

However, though the yield of indoxyl may be as much as 50% of the weight of the l cin, the results are negatived by the faci ity with'whi'ch the glycin is decomposed at the temperatures at which it should be introduced into the caustics. Moreover, in these processes a larger or smaller quantity of monomethylanilin is always produced which shows that it is to this secondary reaction that the bad yield is due.

The present invention relates to a new process by which the arylglycmates or their derivatives are quickly transformed into 1ndoxyl without the formatlon of undesirable try-products. The process is based upon the discovery that arylglycinates and their derivatiyeo me transformed theoretically into the 'oorrbspondingjndoxyls without undergoing decomposition if they are fused With inorganie-su'hstanccs capable of decomposing; water in the presence of dehydratedsodium and potassium hydroxide and if the operation is eii'ccted in an autoclave at a pressure of six to ten atmospheres.

By effecting the operation in an autoclave l achieve. besides the advantage of preventme; tllGdOCOlll'POSltlOIl of the arylglycinates, the further advantage that the introduction thereof into the autoclave is not hindered by frothing. When the process carried on at ordinary pressure frothing greatly prolongs the contact of the arylglyeinates and the indoxyl with the caustic at an undesirable temperature. By working under pressure the process of fusing is shortened and the indoxyl may be transformed into indigo before it is decomposed.

Ewam/plc.

into an autoclave fitted with a stirrer is first introduced a dehydrated and heated mixture of 70 parts caustic potash and 30 parts caustic soda to which is added 30 parts of sodium amid. The pressure in the autoclave is raised preferably to six to ten kilos by means of ammonia or anilin vapors. when the temperature has fallen to 180, parts of potassium phenylglycinate are introduced as quickly as possible while the temperature is prevented from rising substantially above 190 centigrade. The reaction is immediate and as soon as the evolution of ammonia has ceased, the melt is dissolved in iced water and the indigo is precipitated by the usual methods.

\Vhere the term ammonia is, used in the claims, it is to be understood that anilin is the full equivalent for the purpose of this invention.

Claims.

1. In the manufacture of synthetic indigo, the steps consisting in subjecting an arylglycinate to the action of a fused mixture containing an. alkali metal hydroxid and a water decomposing agent in an atmo'sph of ammonia under pressure of about cl: atmospheres.

2. In the manufacture of synthetic indigo, the steps consisting in subjecting potassium phenylglycinute to the action of a fused mixture of sodium and potassium hydroxids and sodium amid, in an atmosphere of ammonia gas at a pressure of about 610 atmospheres.

3. In the manufacture of synthetic indigo, the steps consisting in subjecting potassium phenylglycinute to the action of a fused mixture of sodium and potassium hydroxids and sodium amid, in an atmosphere of ammonia 

